Which of the following enzymes is not useful for the digestion of proteins?

The angle between the lines whose direction cosines are given by the equations $l^2+m^2-n^2=0$ and $l+m+n=0$ is

If the normal to the curve $y(x) = \int_0^x (2t^2 - 15t + 10) dt$ at a point $(a, b)$ is parallel to the line $x + 3y = -5$ for $a > 1$,then the value of $|a + 6b|$ is equal to ...........

The number of four-letter words that can be formed using the letters of the word $BARRACK$ is:

If three unit vectors $\overrightarrow{a}, \overrightarrow{b}, \overrightarrow{c}$ satisfy $\overrightarrow{a}+\overrightarrow{b}+\overrightarrow{c}=\overrightarrow{0}$, then the angle between $\overrightarrow{a}$ and $\overrightarrow{b}$ is

In the conversion of a zinc ore to zinc metal,the process of roasting involves: